springboot项目启动自动执行代码几种方案

╰半夏微凉° 2022-12-10 10:21 273阅读 0赞

在spring或者springboot项目中，经常会有这样的需求，就是项目启动之后，会执行一段代码，做一些初始化的操作，执行完毕，就不再重复执行。

在spring项目中，可以通过实现InitializingBean接口的方式来实现，另外，项目如果是springweb项目，那么可以通过实现ServletContextListener和ServletContextAware接口等来实现。

在springboot项目中，可以通过实现ApplicationRunner接口和CommandLineRunner接口。

还有一种方式，不用实现接口，通过注解@PostConstruct来实现。

下面给出以上列举的6中方式实现代码：

为了实现所有的方式，我们在maven工程中加入spring-boot-starter-web的依赖。

<parent>
    	<groupId>org.springframework.boot</groupId>
    	<artifactId>spring-boot-starter-parent</artifactId>
    	<version>2.1.4.RELEASE</version>
    </parent>
    
    <dependencies>
    	<dependency>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter</artifactId>
    	</dependency>
    
    	
    	<dependency>
    		<groupId>org.springframework.boot</groupId>
    		<artifactId>spring-boot-starter-web</artifactId>
    	</dependency>
    </dependencies>
    
    <build>
    	<plugins>
    		<plugin>
    			<groupId>org.springframework.boot</groupId>
    			<artifactId>spring-boot-maven-plugin</artifactId>
    			<configuration>
    				<source>${java.version}</source>
    				<target>${java.version}</target>
    				<fork>true</fork>
    				<addResources>true</addResources>
    			</configuration>
    		</plugin>
    	</plugins>
    
    </build>

DemoServiceWithApplicationRunner.java

package com.xxx.service;
    import org.springframework.boot.ApplicationArguments;
    import org.springframework.boot.ApplicationRunner;
    import org.springframework.stereotype.Component;
    @Component
    public class DemoServiceWithApplicationRunner implements ApplicationRunner{
    
    	@Override
    	public void run(ApplicationArguments args) throws Exception {
    		System.out.println("5: run with ApplicationRunner , method -> run().");
    	}
    
    }

DemoServiceWithCommandLineRunner.java

package com.xxx.service;
    import org.springframework.boot.CommandLineRunner;
    import org.springframework.stereotype.Component;
    @Component
    public class DemoServiceWithCommandLineRunner implements CommandLineRunner{
    
    	@Override
    	public void run(String... args) throws Exception {
    		System.out.println("6: run with CommandLineRunner , method -> run().");
    	}
    
    }

DemoServiceWithInitializingBean.java

package com.xxx.service;
    import org.springframework.beans.factory.InitializingBean;
    import org.springframework.stereotype.Component;
    @Component
    public class DemoServiceWithInitializingBean implements InitializingBean{
    
    	@Override
    	public void afterPropertiesSet() throws Exception {
    		System.out.println("2: run with InitializingBean , method -> afterPropertiesSet().");
    	}
    	
    }

DemoServiceWithPostConstruct.java

package com.xxx.service;
    import javax.annotation.PostConstruct;
    import org.springframework.stereotype.Component;
    @Component
    public class DemoServiceWithPostConstruct {
    	@PostConstruct
    	public void run() {
    		System.out.println("3: run with PostConstruct , method -> run().");
    	}
    }

DemoServiceWithServletContextAware.java

package com.xxx.service;
    import javax.servlet.ServletContext;
    import org.springframework.stereotype.Component;
    import org.springframework.web.context.ServletContextAware;
    @Component
    public class DemoServiceWithServletContextAware implements ServletContextAware{
    
    	@Override
    	public void setServletContext(ServletContext servletContext) {
    		System.out.println("4: run with ServletContextAware , method -> setServletContext().");
    	}
    
    }

DemoServiceWithServletContextListener.java

package com.xxx.service;
    import javax.servlet.ServletContextEvent;
    import javax.servlet.ServletContextListener;
    import org.springframework.stereotype.Component;
    @Component
    public class DemoServiceWithServletContextListener implements ServletContextListener{
    	@Override
    	public void contextInitialized(ServletContextEvent sce) {
    		System.out.println("1: run with ServletContextListener , method -> contextInitialized().");
    	}
    }

App.java

package com.xxx;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    @SpringBootApplication
    public class App {
        public static void main( String[] args ){
        	SpringApplication.run(App.class, args);
        }
    }

运行代码，打印信息截图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70][]

可以看出的是，使用springboot提供的ApplicationRunner接口和CommandLineRunner接口均在项目启动日志打印完毕之后才执行。而且这几种方式打印的顺序也不会发生改变。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ZlaW5pZmk_size_16_color_FFFFFF_t_70]: /images/20221123/bea081a167354a2fb0b7464bbe544fc8.png